Pipe connection and combination of a connection and a detaching tool

ABSTRACT

The invention is directed to a coupling assembly having a male member ( 1 ) with a spigot ( 5 ) to be received in an opening ( 21 ) in a female member ( 2 ), and a radially deformable retaining element ( 3 ) which is arranged in a recess ( 22 ) in the female member ( 2 ) and is radially elastically deformable and adapted to be urged into the recess ( 22 ) during the coupling operation by a support element ( 12 ) disposed on the spigot ( 5 ). In the locked position, the spigot ( 5 ) is locked against being pulled out of the opening due to the cooperation between the support element ( 12 ) and the retaining element ( 3 ). To uncouple the coupling assembly, an unlocking element ( 15 ) is provided. The support element ( 15 ) is releasably connected with the spigot ( 5 ) in order to enable assembly of the unlocking element ( 15 ).

This invention relates to a coupling assembly for pipelines having twoconnecting members, namely a male member and a female member which areconnectable to and separable from each other, the male member having aspigot to be received in an opening in the female member for lockingengagement therein by means of a radially deformable retaining elementwhich is arranged in a recess in the female member's opening and isadapted to be urged into this recess by radial elastic deformationduring the coupling operation, the spigot being provided with a recessinto which the retaining element, due to elastic recovery, engages inthe locked position of the connecting members so that the spigot islocked by the retaining element against being pulled out of the opening,and the rear side wall of the recess in the spigot, as seen looking inthe coupling direction, being formed by an end surface of an unlockingelement mounted on the spigot in an axially slidable arrangement.Further, the invention relates to a combination of such a couplingassembly and a release tool.

In a coupling assembly known from U.S. Pat. No. 5,570,910 A, the malemember is integrally formed with the spigot, and the unlocking elementis comprised of two sleeves, including an inner sleeve made of metalencompassing the spigot and an outer sleeve made of a plastic materialencompassing the female member and engaging, in the unlocked position,with a locking bead in a groove in the female member. The inner metalsleeve is fully split to enable the sleeve to be expanded and mounted onthe spigot. The outer sleeve made of plastic is not split but has aninward pointing sealing rib that engages on the male member to form adust seal. The disadvantage of this known coupling assembly is theelaborate and expensive production of its unlocking element.

Furthermore, the split design of the inner sleeve means that producingan effective seal at the unlocking element, and particularly one that isalso liquid-tight, is possible only with difficulty.

It is an object of the present invention to provide a coupling assemblyof the type initially referred to that can be manufactured easily andeconomically and which enables by simple means a liquid-tight sealing ofthe coupling assembly's connecting zone.

This object is accomplished in accordance with the present invention inthat the front side wall of the recess in the male member, as seenlooking in the coupling direction, is formed by an annular supportelement which engages in a circumferential groove of the male member andis supported in axial direction inside the circumferential groove, andthat the diameter of that section of the male member in front of thegroove, as seen looking in the coupling direction, is the same size as,or smaller than, the smallest inner diameter of the unlocking element.

In the coupling assembly of the present invention the unlocking elementcan be a closed, rigid annular body adapted to be push-fitted onto thespigot prior to assembling the support element. Hence the unlockingelement is easy to manufacture and can be sealed very effectively, forexample, to liquid- or gastight standard, by simple means using, forexample, an inner lying and an outer lying sealing ring. The couplingassembly of the present invention is also suitable, therefore, forexplosion-protected applications. Considering that the unlocking elementis mounted from the plug-in side of the spigot, the other end of themale member which is suitable for connection with a rigid or flexiblepipeline can be of any desired configuration, being, for example, of anelbow or tee configuration.

A further advantageous possibility provided by the support element ofthe coupling assembly is the ability to choose different materials forthe production of the male member and the production of the supportelement. The particular requirements needing to be met by the point ofsupport cooperating with the retaining element can thus be met by asuitable choice of material, without this making the male member anymore expensive. Thus, for example, it is possible to select a softer,easy-to-process material for the male member, while having the supportelement made of a harder material suitable for high seating stresses.With the coupling assembly of the present invention it is possible todesign the shape of the force transmission surfaces between the supportelement and the male member relatively freely without it being tied tothe shape of the support surfaces cooperating with the retaining elementas defined by the locking and unlocking operation.

In an embodiment of the coupling assembly affording particular ease ofmanufacture, the annular support element as well as the retainingelement is a split ring made of a spring material as, for example,spring steel or spring bronze, with a ring made of round wire ofcircular cross section being particularly suitable. This cross-sectionalshape of the support element and retaining element results in favorableconditions for expanding the retaining element while connecting andreleasing the coupling assembly. If the coupling assembly is intendedfor low compressive loads, the split ring can also be made of a plasticmaterial. The round wire from which the retaining element and thesupport element are fabricated can have the same diameter. The diametersof the round wire cross sections for the retaining element and thesupport element, on the other hand, may differ. In accordance with afurther proposal of the present invention, the support element may alsobe comprised of a closed ring connected with the spigot in apositive-engagement relationship by permanent radial deformation, forexample, by curling a collar in a groove.

In order to secure the retaining element made of a ring of round wire bypositive engagement when in the locked position, according to presentinvention the abutment surface provided on the female member forengagement of the retaining element can be a conical surface whose angleof taper is smaller than the angle between the tangent applied to theretaining element at the point of contact with the support element andthe center axis of the coupling assembly. Consequently, the forcesacting on the retaining element when the spigot is loaded in pullingdirection strive to urge the retaining element radially inwardly againstthe spigot and axially against the abutment surface on the femalemember. Movement of the retaining element into the unlocked position isonly possible, therefore, if the distance between the abutment surfaceon the female member and the support element of the spigot is increaseda certain amount by urging the spigot into the receiving bore in thefemale member. This is opposed, however, by the load acting on thecoupling assembly. It has proven advantageous for the angle of taper ofthe abutment surface to be 40° or smaller and for the angle between thetangent and the center axis to be 45° or greater. According to thepresent invention it is also possible to arrange for the seating surfaceon the spigot for engagement with the retaining element to have aslightly smaller diameter than the inner surface of the unlockingelement which covers the seating surface when unlocking. This ensuresthat the deformations to the seating surface caused by the action of theretaining element under load do not impair the displaceability of theunlocking element.

The unlocking element is comprised preferably of a cylindrical orconical sleeve which can be axially movably arranged on the spigot or inthe receiving bore of the female member and has a radial shoulderserving to introduce the force for moving the sleeve into the unlockedposition. Furthermore, the unlocking element of the present inventioncan have a conical end with an angle of taper designed to promote thedisplacement of the retaining element into the recess of the femalemember by the unlocking element.

In the case of coupling assemblies for connecting a flexible pipeline itmay be necessary to lock the spigot against rotation relative to thefemale member. According to the present invention the spigot can beprevented from rotating relative to the female member in the receivingbore of the female member by means of a projection engaging in a recess.A suitable rotary locking device can also be formed by the unlockingelement. For this purpose the unlocking element can have radialprojections and/or recesses that cooperate with radial projections orrecesses of a form deviating from the cylindrical form in the opening ofthe female member and on the envelope surface of the male member and arein interfitting engagement so that the male member is prevented fromrotating relative to the female member. A particularly simpleconfiguration is one in which the unlocking element is comprised of asleeve formed from sheet metal, wherein the end of the sleeve engagingin the opening of the female member and the corresponding section of theopening are equipped with an interfitting serrated profile and whereinthe opposite end of the sleeve is equipped with a polygonal boreembracing a hexagonal section of the male member in a manner preventingrelative rotation.

According to a further proposal of the present invention, the couplingassembly in locked position can be biased in axial direction by a springelement bearing with one end against the female member while its otherend takes support on the male member via the unlocking element, strivingto urge the male member out of the female member against the couplingdirection. The spring element operates to maintain the locked couplingassembly in a zero clearance position, making it difficult for theunlocking element to be moved into the unlocked position. Provision canbe made in addition for a securing element which has to be removed toenable the unlocking element to be moved into the unlocked position. Asspring element it is possible to use a ring made of an elastomericmaterial which also effects a seal between the unlocking element and thefemale member. A sealing ring can be arranged in a groove in the spigotin order to seal the unlocking element vis-à-vis the male member.

A further object of the present invention is to provide a combination ofa coupling assembly of the type initially referred to and a release toolthat enables the coupling assembly to be released with ease and littleconstructional effort.

This object is accomplished in accordance with the present invention inthat the shoulder of the unlocking sleeve and/or an annular collar ofthe spigot has a recess open in radially outward direction in theabutment surface on the side close to the annular collar or theshoulder, and in that the release tool has a fork with two prongs whichenclose a space for accommodating the spigot and, embracing the spigot,are insertable in the recess in radial direction so as to enable theunlocking sleeve to be moved in the release direction by a torque actingon the release tool around an axis linking the points of engagement ofthe prongs in the recess.

The advantage of the combination of the present invention is that thecoupling assembly can be of very compact construction in its axial andradial dimensions. No large area of application is needed on theunlocking sleeve to apply a releasing force, nor is an additional spacerequired in the axial direction because the recess for inserting therelease tool can be constructed without it affecting the overall lengthof the coupling assembly. A further advantage of the configurationaccording to the present invention is that a comparatively high releaseforce can be achieved with a release tool of small size thanks to theresulting favorable conditions of leverage and force transmission. Henceit is possible to equip the coupling assembly with a comparativelystrong spring element held in tension between the shoulder of theunlocking sleeve and the female member without this having a detrimentaleffect on releasing the coupling assembly. A further advantage finallyis that the recess for inserting the release tool, which recess islocated on the annular collar of the spigot for example, requires nonotable production effort because the recess can be manufactured at thesame time as performing the other processing operations. The releasetool itself can also be made simply and inexpensively using, forexample, a sheet metal material.

A particularly advantageous embodiment has the recess formed by aconical surface. It is possible accordingly for the prongs of therelease tool to have gripping surfaces cooperating with the conicalsurface of the recess and having an inclination corresponding to theangle of taper of the conical surface. Provision can further be made forthe gripping surfaces of the prongs, which engage the shoulder or theannular collar inside the recess, to form an angle which opens towardthe ends of the prongs. The advantage of this construction is that therelease tool can adapt to various diameters. Furthermore, constructingthe release tool in this manner also makes it possible for the unlockingsleeve to be moved into the release position by an exclusively radialmovement of the release tool when the recess is formed by a conicalsurface and/or the prongs have correspondingly inclined grippingsurfaces. This is an advantage in installation conditions lacking thenecessary freedom of movement for swiveling the release tool. It hasalso proven to be particularly convenient for the handle of the releasetool to be arranged at an angle to the prongs of the fork that enablesthe torque required to release the coupling assembly to be generated bya force applied by hand to the handle in substantially verticaldirection to the axis of the coupling assembly. The handle is arrangedpreferably at an angle of 110° to the prongs.

According to an embodiment affording ease and economy of manufacture,the release tool is comprised of a rectangular plate having along itsshort side a central indentation forming the space between the prongs.

Embodiments of the present invention will be described in more detail inthe following with reference to the accompanying drawings. In thedrawings,

FIG. 1 is a longitudinal sectional view of the female member and

FIG. 2 is a longitudinal sectional view of the male member of a couplingassembly of the present invention;

FIG. 3 is a detail, on an enlarged scale, of the coupling assembly ofFIGS. 1 and 2 in the locked position;

FIG. 4 is a longitudinal sectional view of a coupling assembly of thepresent invention with a rotary locking device;

FIG. 5 is a cross sectional view of the coupling assembly taken alongthe line V—V of FIG. 4;

FIG. 6 is a view, partly in section, of a coupling assembly of thepresent invention suitable for cooperation with a release tool;

FIG. 7 is a view of the coupling assembly of FIG. 6 in the unlockedposition, showing a release tool applied;

FIG. 8 is a projection of the coupling assembly, showing the releasetool of FIG. 7 applied;

FIG. 9 is a front view of a release tool of the present invention;

FIG. 10 is a top view and

FIG. 11 is a side view of the release tool of FIG. 9;

FIG. 12 is a longitudinal sectional view of a further embodiment of acoupling assembly with a rotary locking device; and

FIG. 13 is a cross sectional view of the coupling assembly of FIG. 12.

The coupling assembly shown in FIGS. 1 to 3 is comprised of a malemember 1 and a female member 2 which can be connected together by meansof a retaining element 3. The male member 1 takes the form of a pipehaving a nipple 4 at one end for fastening a pressure line. The otherend of the male member 1 is constructed as a spigot 5 carrying a sealingring 7 in an annular groove 6. The annular groove 6 is located in acylindrical end section 8 of the outer surface of the spigot 5. Adjacentto the end section 8 is a conical surface 9 whose diameter increasestoward the nipple 4 and which merges into a short cylindrical surface 10of larger diameter. The cylindrical surface 10 is limited at the endremote from the conical surface 9 by a groove 11 extending radiallyinwardly and accommodating therein a support element 12. The supportelement 12 is constructed as a split, elastically deformable round-wiresnap ring made of stainless spring steel, spring bronze or plastic, forexample, and engages with the radially inner half of its cross sectionin the groove 11 which is adapted to fit the cross-sectional shape ofthe round-wire snap ring. To assemble, the support element 12 is put onthe end section 8 of the spigot 5 and pushed over the conical surface 9,whereby it is expanded, and over the cylindrical surface 10 until itsnaps into the groove 11 where it rests with a slight radial biasagainst the wall of the groove 11.

Adjacent to the groove 11 is a cylindrical surface 13 whose diametercorresponds to the diameter of the cylindrical surface 10. Thecylindrical surface 13 is limited in the direction of the nipple 4 by anannular collar 14 of larger diameter. A sleeve-shaped unlocking element15 with a radial shoulder 16 is seated on the cylindrical surface 13 inan axially movable arrangement. At its end close to the support element12 the unlocking element 15 has a conical end surface 17 which taperstoward the support element 12 and has an angle of taper amounting toabout 45° relative to the longitudinal axis of the spigot 5. Between thesupport element 12 and the unlocking element 15 is a space forming arecess 18. The unlocking element 15 has a cylindrical envelope surface19 and its outer diameter is a few tenths of a millimeter larger thanthe outer diameter of the support element 12. Arranged on the unlockingelement 15 is an annular spring element 20 made of an elastomericmaterial adapted to bear against the shoulder 16. Inside an annulargroove in the cylindrical surface 13 is a sealing ring 34 which sealsoff the sliding gap between the cylindrical surface 13 and the bore inthe unlocking element 15 to the outside.

To accommodate the spigot 5, the female member 2 has a full-lengthreceiving bore 21 whose inner diameters are sized to fit the outerdiameters of the various sections of the spigot 5. Inside the receivingbore 21 is an annular recess 22 in which the retaining element 3 ispositioned. The radial depth of the recess 22 is calculated to enablethe retaining element 3 to be displaced fully into the recess 22. Therear side wall 23 of the recess 22, as seen looking in the couplingdirection, extends vertically to the longitudinal axis of the receivingbore 21. The front side wall 24 of the recess 22, as seen looking in thecoupling direction, has an abutment surface 25 with a 30° chamfer forthe retaining element 3 in the locked position. The cylindrical boresurfaces 26, 27 on either side of the recess 22 have different diameterscorresponding to the different outer diameters of the support element 12and the envelope surface 19. Like the support element 12, the retainingelement 3 is constructed as a split round-wire snap ring. In therelieved state the retaining element 3 has an inner diametercorresponding essentially to the diameter of the cylindrical surface 13of the spigot 5.

To couple the male member 1 and the female member 2, the spigot 5 isinserted into the receiving bore 21 and urged inside with elasticdeformation of the spring element 20 until the retaining element 3,expanded by the conical surface 9 and the support element 12 anddisplaced into the recess 22, locks into the recess 18 with a snapaction. The locked position thus adopted is shown in FIG. 3. In thisposition the retaining element 3 is held in tension by the action of thebiased spring element 20 between the support element 12 of the spigot 5and the abutment surface 25 of the female member 2 so that it is urgedagainst the cylindrical surface 13 of the spigot 5 and is unable toyield radially outwardly into the free area of the recess 22.Self-releasing of the coupling assembly with the unlocking element 15positioned as shown is possible, therefore, only if a component isdestroyed.

The coupling assembly can be disconnected by urging the spigot 5, andwith it the unlocking element 15, into the receiving bore 21 withsimultaneous deformation of the spring element 20. As this occurs, theretaining element 3 is relieved of the biasing force of the springelement 20 and, together with the spigot 5 and the support element 12,is moved in the recess 22 by the unlocking element 15 until it abuts theside wall 23. Subsequently, urging the unlocking element 15 togetherwith the spigot 5 further into the receiving bore 21 causes theretaining element 3 to be expanded by the conical end surface 17 of theunlocking element 15 and to be displaced radially outwardly into therecess 22. Once this unlocked position is reached, the spigot 5 togetherwith the unlocking element 15 and the support element 12 can be pulledout of the female member 2. As FIG. 1 shows, the retaining element 3remains in the recess 22 of the female member 2.

Instead of a ring made of an elastomeric material it is possible to usea disk spring as spring element 20. Furthermore, the unlocking stroke ofthe unlocking element required to unlock the coupling assembly can alsobe obtained by arranging a removable spacer between the spring element20 and the shoulder 16. It is possible furthermore for the springelement 20 to be replaced by a spring element at some other location,for example, in the receiving bore 21, which tensions the male memberand the female member axially in the locked position. As a furtherpossibility, as shown in FIG. 12 the unlocking element 15 can bescrew-fitted to the spigot 5 by means of a thread 46. The unlockingstroke is then effected by turning the unlocking element.

In the embodiment shown in FIGS. 4 and 5, the unlocking element 15 madeof a sheet metal material is constructed as a rotary locking devicewhich prevents the spigot 5 inserted in the female member 2 fromrotating relative to the female member 2. The end of the unlockingelement 15 on the side close to the retaining element 3 is equipped onits outside with an obtuse-angled serration 30 formed by radialdeformation of the sheet metal material. The serration 30 comprises aplurality of axially parallel teeth. The bore surface 27 of thereceiving bore 21 in the female member 2 has an internal serrationregistering with the serration 30, with a plurality of notches intowhich the teeth of the serration 30 engage. Hence when the unlockingelement 15 is inserted in the female member 2, it is connected with thefemale member 2 in a manner allowing axial displacement but preventingrelative rotation. The shoulder 16 of the unlocking element 15 abuttingthe annular collar 14 of the male member 1 is equipped with a flange 31embracing the collar 14 and shaped in the form of a bihexagonal prismwith a correspondingly shaped inner surface 32. The collar 14 of themale member 1 is configured as a hexagonal prism 33, with theedge-to-edge diameter of the prism 33 corresponding to that of the innersurface 32 of the flange 31. The edges of the prism 33 thus engage inevery second corner of the bihexagonal inner surface of the flange 31,thereby producing a non-rotatable connection between the flange 31 andthe collar 14. The advantage of the described embodiment of the rotarylocking device is that it is easy to manufacture and permits thecoupling assembly to be coupled in numerous angular positions. Noadditional components are needed to form the rotary locking device.

The embodiment presented in FIGS. 6 to 8 is intended to effectuncoupling by means of a special release tool and is adapted in itsconstruction to said tool. Except for the features described in moredetail in the following, this embodiment corresponds in its basicstructure to the embodiments described above.

As shown in FIG. 6, the seating surface 13 of the spigot 5 in thisembodiment is of a slightly conical configuration, its diameter beingslightly larger than the diameter of the cylindrical surface 10,increasing at an angle of taper X in a direction opposite to thecoupling direction. The unlocking sleeve 15 seated on the seatingsurface 13 is also of conical shape with the same angle of taper so thatthe clearance between the sleeve bore and the seating surface 13increases when the unlocking sleeve 15 is moved into the unlockedposition. The unlocking sleeve is therefore easy to release and moveeven in the presence of corrosion. The shoulder 16 of the unlockingsleeve 15 bears against an abutment surface 28 of the annular collar 14when the coupling assembly is closed. At the outer edge of the abutmentsurface 28, a 30° chamfer forms a recess 29 in which a release tool 38can be inserted as shown in FIG. 7.

The release tool 38 shown in FIGS. 9 to 11 is comprised of a rectangularplate with a central indentation 39 on one of its short sides, thusforming a fork 40 with two prongs 41. That part of the plate adjoiningthe fork 40 forms the handle 42 of the release tool 38 and is bent aboutan axis parallel to the short sides of the plate so that the handle 42and the fork 40 enclose an angle of around 110°. The handle 42 has ahole 43 for hanging up the release tool 38. On their facing sides formedby the indentation 39, the prongs 41 have flat gripping surfaces 44inclined at an angle of 7.5° to the center axis of the fork 40 so thatthe distance between the gripping surfaces 44 increases toward the openend of the indentation 39. At the same time the gripping surfaces 44 areinclined at an angle of 60° to the plate bottom 45.

To disconnect the coupling assembly the release tool 38 with the fork 40is seated onto the annular collar 14 of the spigot 5, whereby the prongs41 embrace the annular collar 14 and their gripping surfaces 44 engagein the recess 29 with the annular collar 14, while the abutment surfaceformed by the plate bottom 45 engages the shoulder 16 of the unlockingsleeve 15. If the handle 42 is now pressed by hand toward the malemember 1, the fork 40 turns around an axis defined by the two points ofcontact between the gripping surfaces 44 and the annular collar 14,whereby the prongs 41 bearing against the annular collar 14 are urgedagainst the shoulder 16 of the unlocking sleeve 15, moving it into therelease position. Once the release position is reached and the retainingelement 3 is displaced from its locked position into the recess 22 inthe female member 2, the reactive force supported on the spigot 5 duringthe release operation can no longer be transmitted therefrom via theretaining element 3 to the female member 2, causing the spigot 5 to bemoved by the spring element 20 in the release direction inside thereceiving bore 21 of the female member 2 so that it can then be pulledout of the receiving bore 21 with ease. This operation is illustrated inFIG. 8 showing the beginning of the release operation in broken linesand the adoption of the release position in solid lines.

FIG. 7 shows the adoption of the release position by a radial movementof the release tool 38. In this case the release tool 38, and hence theunlocking sleeve 15, is axially moved in the release direction by thewedge action of the doubly inclined gripping surfaces 44 on the prongs41, without any turning of the release tool 38 occurring, as shown inFIG. 8. A straight release tool with an unbent handle 42 as indicated bythe dot-and-dash line in FIG. 11 is particularly suitable for performingsuch a release movement. It will be understood, of course, that it isalso possible to perform a swivel movement with a straight release toolof this type, as is shown in FIG. 8. The straight release tool may alsobe an advantage in limited space and is particularly easy to apply.

In the embodiment of the coupling assembly shown in FIGS. 12 and 13, theend section 8 of the spigot 5 has an external serration 35 located infront of the annular groove 6 as seen looking in the coupling direction,and which in the illustrated locked position is in meshing engagementwith an internal serration 36 of corresponding configuration formedinside the receiving bore 21 of the female member 2. The axiallyparallel teeth of the two serrations 35, 36 cooperate to form a rotarylock between the male member 1 and the female member 2, with theplurality of teeth ensuring the transmission of a sufficiently hightorque in spite of the small radial dimensions and enabling, thanks tothe small angular distance w between the teeth, a large number ofcoupling positions. By reason of its arrangement inside the area of thecoupling assembly sealed by the sealing ring 7, the rotary lockingdevice is also effectively protected from contamination and corrosion.

Numerous further embodiments of the coupling assembly of the presentinvention are possible in addition to the examples described. Any knownform of pipe fitting, whether straight, elbow, tee or the like, can beimplemented with the described coupling assembly. It is also possiblefor the male member to be constructed as a threaded element or as a partformed integral with a housing, and for the female member to form thedisconnectable plug. Male and female members can also be composed ofseveral parts joined together by screwing, flanging, adhesive bonding,welding or the like. Using such a design approach also makes it possiblefor the coupling assembly of the present invention to be adapted to ashaped bore already existing on an apparatus. For example, a union screwforming the receiving bore for the spigot can be threaded into anexisting connecting bore with an internal thread which, together withthe union screw, then forms the female member of the coupling assembly.

What is claimed is:
 1. A coupling assembly for pipelines having twoconnecting members, including a male member and a female member whichare connectable to and separable from each other, the male member havinga spigot to be received in an opening in the female member for lockingengagement therein by a radially deformable retaining element which isarranged in a recess in the opening of the female member and is urgedinto said recess by radial elastic deformation during the couplingoperation, said spigot being provided with a recess into which theretaining element, due to elastic recovery, engages in the lockedposition of the connecting members so that the spigot is locked by theretaining element against being pulled out of the opening, and the rearside wall of the recess in the spigot, as seen looking in the couplingdirection, being defined by an end surface of an unlocking elementmounted on the spigot in an axially slidable arrangement, characterizedin that the front side wall of the recess in the spigot, as seen lookingin the coupling direction, is formed by an annular support element whichengages in a circumferential groove in the spigot and is supported inaxial direction inside the circumferential groove, and that the diameterof that section of the spigot in front of the circumferential groove, asseen looking in the coupling direction, is at most the same size as thesmallest inner diameter of the unlocking element.
 2. The couplingassembly as claimed in claim 1, characterized in that at least one ofthe support element and the retaining element is a split ring made of aspring material.
 3. The coupling assembly as claimed in claim 2,characterized in that the split ring has a circular cross section. 4.The coupling assembly as claimed in claim 1, characterized in that theabutment surface provided on the female member for engagement of theretaining element is a conical surface whose angle of taper is smallerthan the angle between the tangent applied to the retaining element atthe point of contact with the support element and the center axis of thecoupling assembly.
 5. The coupling assembly as claimed in claim 1,characterized in that the recess on the spigot for engagement with theretaining element has a slightly smaller diameter than the inner surfaceof the unlocking element which covers the seating surface whenunlocking.
 6. The coupling assembly as claimed in claim 1, characterizedin that a spring element biased axially in the locked position bearswith one end against the unlocking element and the male member and withits other end against the female member.
 7. The coupling assembly asclaimed in claim 6, characterized in that the unlocking element iscomprised of a cylindrical sleeve which is axially movably arranged onthe spigot and has a radial shoulder serving to introduce the force formoving the sleeve into the unlocked position.
 8. The coupling assemblyas claimed in claim 7, characterized in that a removable securing meansis provided for preventing the unlocking element from being moved intothe unlocked position.
 9. The coupling assembly as claimed in claim 7,characterized in that the unlocking element is connected with the spigotby means of a thread.
 10. The coupling assembly as claimed in claim 7,characterized in that the spring element takes support upon the shoulderof the unlocking element which in turn bears against an annular collarof the male member.
 11. The coupling assembly as claimed in claim 10,characterized in that a seal ring is provided between the unlockingelement and the male member and the spring element seals the unlockingelement with respect to the female member in the locked position. 12.The coupling assembly as claimed in claim 1, characterized in that thespigot is prevented from rotating relative to the female member in thereceiving bore of the female member by at least one projectionassociated with one of the male member and the female member engaging inat least one corresponding recess in the other of the male member andthe female member.
 13. The coupling assembly as claimed in claim 12,characterized in that the at least one projection is an externalserration on the front end section of the spigot in front of a sealingring, as seen looking in the coupling direction, which is in meshingengagement with the at least one corresponding recess defined by aninternal serration formed in the receiving bore of the female member.14. The coupling assembly as claimed in claim 12, characterized in thatthe unlocking element has at least one of radial projections andrecesses that cooperate with a corresponding ones of said at least oneprojection and at least one recess, said projections and recesses beingof a form deviating from the cylindrical form in the opening of thefemale member and on the envelope surface of the male member and are ininterfitting engagement so that the male member is prevented fromrotating relative to the female member.
 15. The coupling assembly asclaimed in claim 14, characterized in that the unlocking element iscomprised of a sleeve formed from sheet metal, wherein the end of thesleeve engaging in the opening of the female member and thecorresponding section of the opening are equipped with an interfittingserrated profile, and the opposite end of the sleeve has a polygonalinner surface embracing a polygonal section of the male member in amanner preventing relative rotation.
 16. A combination of a couplingassembly for pipelines and a release tool, in which the couplingassembly has a male member comprising a spigot to be received in anopening in the female member for locking engagement therein by anelastically deformable retaining element which is arranged in a recessin the opening of the female member and is urged into said recess byradial deformation during the coupling operation, and said retainingelement engaging in the locked position of the spigot, due to elasticrecovery within a recess in the spigot, so that the spigot is locked bythe retaining element against being pulled out of the opening, and inwhich the rear side wall of the recess in the spigot, as seen looking inthe coupling direction, is defined by an end surface of a cylindricalunlocking sleeve mounted on the spigot in an axially slidablearrangement, said unlocking sleeve having a radial shoulder abutting anannular collar of the spigot for the introduction of a displacementforce, characterized in that one of the shoulder of the unlocking sleeveand the annular collar of the spigot has a recess open in radiallyoutward direction in the abutment surface on the side close to the oneof the annular collar and the shoulder, and in that the release tool hasa fork with two prongs which enclose a space for accommodating thespigot and, embracing the spigot, are insertable in the recess in radialdirection in such manner that the unlocking sleeve is movable in therelease direction by a torque acting on the release tool around an axislinking the points of engagement of the prongs in the recess.
 17. Thecombination as claimed in claim 16, characterized in that the recess onthe one of the annular collar and the shoulder is formed by a conicalsurface.
 18. The combination as claimed in claim 17, characterized inthat the prongs of the release tool have flat gripping surfacesengageable with the conical surface of the recess and having aninclination corresponding to the angle of taper of the conical surface.19. The combination as claimed in claim 18, characterized in that thegripping surfaces of the prongs, which engage the one of the shoulderand the annular collar inside the recess, form an angle which openstoward the ends of the prongs.
 20. The combination as claimed in claim16, characterized in that the release tool has a handle which isarranged at an angle to the fork so as to enable the torque required torelease the coupling assembly to be generated by a force applied by handto the handle in substantially vertical direction to the axis of thecoupling assembly.
 21. The combination as claimed in claim 16,characterized in that the release tool is comprised of a rectangularplate having along its short side a central indentation forming thespace between the prongs.